So I just replaced the headers and ypipe on my LS1 Z28...it was backfiring and I thought it was bad 02's...so I bought new 02's w/plugin extensions...now the hesitation/studder problem is gone when I accelerate for the most part...but it still has gunshot backfires@! After talking to a tuner, he said it could be a leak by the header/pipe intersection due to the fact i used the cheaper pacesetter exhaust clamps instead of thick 4" clamps...i put my hand around the clamp while it's idling and i can't feel any leak...would a small leak under acceleration cause backfires? Or is this a plug/ignition issue? How can I diagnose the problem? Thanks.

 

bump, someone help a brother out

 

Well if all you did was replace the headers and did new exhaust pipes then you shouldn't have a backfire. Ahkams razor states that the most simple answer is probably the right one so check the headers and entire exhaust system for leaks. I'm assuming you did new header gaskets I hope. You may be running lean and you are getting too much fuel into the pipes from the exhaust valves or your plugs aren't firing strong enough too burn all the fuel in the system so all the residual is going into the pipes. I would also check your plugs. Pull them all and check for any burn marks etc.

You can also try the old school paper test. Take a piece of sheet paper and hold it about 4" from the exhaust pipe. While the engine is idling it should only flex away from you on each exhaust stroke. If at any point the paper flexes back in towards the pipe then you may have an exhaust valve that isn't operating properly.

Did you have a tuner make any changes to your VE tables or anything recently?

 

I was told to reuse the stock steel gaskets when replacing headers, that they work better than the cheap ones that are supplied with the set...was I misinformed?

 

No you weren't misinformed about the metal gaskets being better but just like with anything else that gets swapped on a car you might as well do new stuff while you can. The gaskets are cheap enough to replace. If the car has any sort of miles on it you might as well do it. That metal expands and contracts and almost conforms it's own shape over time with the original headers so I would say replace the gaskets and change your plugs.

 

would i know if the headers were leaking by listening?? I mean, if I rev it from the engine can't i just listen or feel for air?? I'll check for carbon buildup when I get off work around the exhaust ports

 

Still backfiring, i have tightened every ******* shitty exhaust clamp and the only leak i feel is back in the catback/ypipe intersection...which isn't anywhere near the O2's so it shouldn't matter. So WHAT THE **** is causing this?!?! Does it matter that I left my rear O2's unhooked?? Or should they be plugged in? B/c I thought they didn't affect engine managment.

 

Actually the rear 02s have to do with your MAF. The front 02s you can remove no problem because people do it all the time when they take out their catalytic converters. You definitely don't want to disconnect the rear 02s that that are on your long tubes. Connect those back up and see how it runs. The rear 02s manage your rich/lean air mixture so leave them connected or the computer is gonna freak the hell out.

 

Might want to put new header gaskets in, will be a pain in the *** tho.

 

UPDATE!! After having 2 friend's come over and look at the car and take it for a drive...the hesitation is a misfire...well, I remembered that autozone's handheld said there was a misfire in cyl 3...so we took out the plug and guess what...it was ******* cracked! We pulled another, and it looked better, but still very past a tuneup in my opinion... So we are going to change all of the plugs either tomorrow night or Tuesday... WHAT PLUGS would you guys recommend using Pacesetter LT's?? They put out more heat than stock headers, correct? Thanks.

 

Yep a cracked plug will do it I'm glad you checked em. I wouldn't recommend anything less than the platinum bosch plugs. I use the iridiums in mine, they are about $10.00 a piece but they fire hot and they last a long time. If you are worried about the headers putting off too much heat then you need to buy some good plug wires. The plugs themselves aren't affected as much. Most of the heat you will feel from underneath your floorboard more than anywhere else. In the winter time I don't even have to run my heater in my car lol. But I've only got about 1/8" clearance between the header flange and the K member

 

Thank god. Can I buy those at Autozone or Advanced?? What's better, NGK's or Bosch? And ya, I wanna buy the nice ones, $10/pc ain't **** for the performance of a good running car!

 

NGK's are for imports DO NOT BUY THOSE. Either Bosch or AC Delco. Champions aren't a bad plug but Bosch and AC Delco are better. Yep you can buy them at Kragen, Autozone or CSK whichever is in your area. I don't have an Advanced auto in my area so I wouldn't know what they carry...

 

Watch out, after these plugs go in I want that rematch! lol I was racing you with a ******* misfire!! Hopefully I didn't hurt my engine? :/

 

OK. Side note, basic NGK's were what was in the car already....are those factory?

 

I'm going to have to disagree

Buy the NGK TR55's thats what the majority of people here run

https://ls1tech.com/forums/showthrea...ark+best+plugs

 

I just want to clarify something here, you have the O2's mixed up. The FRONT O2's are used for closed loop operation, they report to the pcm about fueling and are what ultimately affect the fuel trims, so DO NOT remove them. The REARS can be removed, as all they do is monitor the cats.

edit: also, NGKs are not just for imports, they are a copper core plug and will fire hotter than the iridiums or platinum plugs. They will also provide more performance. You really can't beat a copper core plug for performance, however they do not last quite as long as the others. This is not a concern though really, because the ignitions in these cars are so hot that the NGKs will last a very long time if your fueling is spot on. I know of people pulling them after 50k mils and they still look great.

 

Just bought the best Autozone had in my area, the Bosch Iridium plugs (7.99/pc). So since it has 4 prongs they said don't gap it...that's wierd, but w/e. I'll let ya'll know if it works I'm installing them after work late tonight.

 

Dig race this time? LoL...

 

I wouldn't listen to anything Halloran's says....